A double-blind, placebo-controlled, randomised withdrawal study of adjunctive brexpiprazole maintenance treatment for major depressive disorder.

Objective: To compare time to relapse in patients with major depressive disorder (MDD) stabilised on antidepressant treatment (ADT) + brexpiprazole who were randomised to continued adjunctive brexpiprazole or brexpiprazole withdrawal (switch to placebo).

Methods: This Phase 3, multicentre, double-blind, placebo-controlled, parallel-arm, randomised withdrawal study enrolled adults with MDD and inadequate response to 2–3 ADTs. All patients started on adjunctive brexpiprazole 2–3 mg/day (Phase A, 6–8 weeks). Patients whose symptoms stabilised (Phase B, 12 weeks) were randomised 1:1 to adjunctive brexpiprazole or adjunctive placebo (Phase C, 26 weeks). The primary endpoint was time to relapse in Phase C. Depression rating scale score changes were secondary endpoints.

Results: 1149 patients were enrolled and 489 patients were randomised (ADT + brexpiprazole n = 240; ADT + placebo n = 249). Median time to relapse was 63 days from randomisation in both treatment groups for patients who received ≥1 dose. Relapse criteria were met by 22.5% of patients (54/240) on ADT + brexpiprazole and 20.6% (51/248) on ADT + placebo (hazard ratio, 1.14; 95% confidence interval, 0.78–1.67; p = 0.51, log-rank test). Depression scale scores improved during Phases A–B and were maintained in Phase C. Mean weight increased by 2.2 kg in Phases A–B and stabilised in Phase C.

Conclusion: Time to relapse was similar between continued adjunctive brexpiprazole and brexpiprazole withdrawal; in both groups, ∼80% of stabilised patients remained relapse free at their last visit. Adjunctive brexpiprazole therapy was generally well tolerated over up to 46 weeks, with minimal adverse effects following brexpiprazole withdrawal.ClinicalTrials.gov identifier: NCT03538691. Funding: Otsuka, Lundbeck.